Recently, a substrate for a display device has been used while a functional film is attached thereto in order to implement various functions. As electronic devices have a tendency to be decreased in size and be improved in performance, there is a need for lighter, thinner, shorter and more compact electronic products as a technical problem.
Meanwhile, in conventional process of bonding a substrate glass with a film, a transparent adhesive sheet having a thickness of approximately 100 μm was used to attach them. However, there is a problem in that it is insufficient to meet the current customers' need for high functionality, small size, and slim thickness of a display material. Thus, a printing technology such as bar coating or slot die coating has been used to bonding a substrate glass with a film with a small uniform thickness of 10 μm or less
However, the method also has a limitation in that a substrate and a functional film cannot be bonded to each other with a uniform thickness, and a sufficiently small thickness cannot be implemented.